Techniques used to Study the Brain: MRI
What is MRI scanning?
- Magnetic Resonance Imaging (MRI) uses a large magnet and pulses of radio waves to scan the brain, producing images of brain structures
- MRI produces a picture of the inside of the brain or body by measuring hydrogen nuclei in the area that is being scanned
- The patient being scanned is placed inside a ‘doughnut’-type tube and they are asked to keep very still as any movement may affect the precision of the measurement
- The scanner makes a loud, banging noise while it is scanning which may be distressing for the patient
- Patients are asked to remove all metal objects from their person so MRI scanning would not be suitable for anyone with metal implants in their body
- MRI scans can show areas the size of brain structures, the volume of grey matter within those structures, brain damage, bleeding and tumours
Which studies use MRI?
- MRI was used to scan the brains of taxi drivers (Maguire 2000) in order to determine a correlation between spatial navigation and hippocampal grey matter
- Luby et al. (2013) used MRI to assess the affects of poverty on a child’s developing brain
Both of these studies are available as separate Key Studies – just navigate the Brain and Behaviour section of this topic to find them.
Examiner Tip
Remember that MRI scans only measure structure, not function.
What are the strengths and limitations of MRI?
Strengths:
- MRI enables researchers to pinpoint specific brain structures which may be damaged or have increased grey matter to identify the link between brain and behaviour
- MRI is less invasive than techniques such as PET as it does not require the use of radiation
Limitations:
- MRI scanners are prone to disturbance caused by noise, temperature and human error in calibration which means that they are not always reliable
- MRI scanners would not be suitable for someone who suffers from claustrophobia due to the enclosed environment of the machine
Examiner Tip
MRI uses objective measures (the use of a machine, the production of the scan) but they are still prone to possible bias on the part of the researcher e.g. in the interpretation of the resulting scan images.
Worked example
Explain the use of one technique used to study the brain. [9]
Here is an example of a paragraph which could be used to explain what is involved in the procedure of MRI scanning. Note that the language is clear, concise and uses key terminology:
Magnetic Resonance Imaging Scan (MRI) uses a scanning machine which contains two powerful magnets, pulsing radio waves and a computer to produce images of brain structures. The two magnets in MRI attract protons in the organism. The first magnet aligns water molecules in the body, and the second magnet is turned on and off in a series of quick pulses, causing hydrogen atoms to switch back to their relaxed state. This procedure as a whole enables images of brain structures to be taken and then analysed.
